On the whole, the main code of most games was not written by Ambrosia. There was a form on the website where you could submit a simple demo of a game idea you had. If Ambrosia thought it had potential then we would sign you up, to support the development, publishing and distribution.
Ambrosia had a series of libraries, which were a mixture of C and Assembler, for graphics and sound etc. We had an in house graphic artist. And, of course, the shareware licensing code and mechanism.
It was a great model. Coders with an idea could get support to take their game to the next level, and sell it etc. It all seems so easy now but the net was in its infancy then. We were mailing out CDs filled with the games.
I never got my hands dirty of the game code, but I know the libraries we had were well polished and optimised, and so were very valuable to coders (no stack overflow back then!).
So, I'm not sure how much of the code is near-original Macintosh version code, and how much was revised/replaced to support SDL. Probably lots of original stuff though, surely.
Any details on what the code was like for these games? I'd love a peek behind the curtain. At the time, it felt incredibly well-polished.